Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
569 views
in Technique[技术] by (71.8m points)

ruby - How to prepend classmethods

This question directly relates to this one. But I tried to break it down to the base problem and I didn't want to enter even more text into the other question box. So here goes:

I know that I can include classmethods by extending the module ClassMethods and including it via the Module#include hook. But can I do the same with prepend? Here is my example:

class Foo:

class Foo
  def self.bar
    'Base Bar!'
  end
end 

class Extensions:

module Extensions
  module ClassMethods
    def bar
      'Extended Bar!'
    end
  end

  def self.prepended(base)
    base.extend(ClassMethods)
  end
end
# prepend the extension 
Foo.send(:prepend, Extensions)

class FooE:

require './Foo'

class FooE < Foo
end

and a simple startscript:

require 'pry'
require './FooE'
require './Extensions'

puts FooE.bar

When I start the script I don't get Extended Bar! like I expect but rather Base Bar!. What do I need to change in order to work properly?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

A simpler version:

module Extensions
  def bar
    'Extended Bar!'
  end  
end

Foo.singleton_class.prepend Extensions

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...